Modular host local expansion upgrade

ABSTRACT

A personal computer system utilizes a simplified motherboard having connectors on the motherboard that are electrically connected to data, address, control, power and ground signals necessary for expansion and upgrade of the computer system and a riser card or cards having the desired interface connectors and logic circuits thereon. The present invention provides for operatively and removably coupling a plurality of I/O expansion cards, host local bus interfaces and future system upgrades for the computer system without burdening the base cost thereof. The computer system may be expanded or upgraded at any time during manufacture or in the field. A simple and low cost common motherboard is utilized in the manufacture of the computer systems, resulting in lower manufacturing costs. A base computer system may be easily upgraded when more features are desired. A riser card is configured for the desired features, plugged into the motherboard connectors, and the desired new peripheral features plugged into the riser card to complete the upgrade.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates generally to computers, and in particular, tomodular expansion upgrades thereof.

2. Background of the Invention

Personal computers are becoming more prevalent in the work place withmore and more people depending on their livelihoods from the usethereof. Advances in computer technology have created the ability andthus the demand for increased memory capacity, faster programcomputation, higher display resolution and faster presentation ofinformation to the computer user. The demand for personal computers mayalso be attributable to its ease of use and adaptability to a multitudeof tasks, both now and in the future.

The flexibility, adaptability and upgradability of the personal computeris in large part a function of the ease in which new developments intechnology and functionality may be incorporated therein, both duringmanufacture at the factory and after purchase at the computer user'soffice or home. The personal computer market place has enjoyed anabundance of new and improved technologies largely because of an opensystem architecture and widely publicized interface standards.

The first of the personal computer interface standards was the IndustryStandard Architecture (ISA) bus. The ISA bus utilizes an 8 bitinput-output (I/O) bus having a maximum of 8 MHz data throughput. As thespeed and sophistication of the personal computer system centralprocessing unit (CPU) increased, a faster and higher data throughputcapacity bus became necessary. The Extended Industry StandardArchitecture (EISA) bus was developed to enable greater data throughput.The EISA bus utilizes a 32 bit I/O bus having a maximum of 8 MHz datathroughput per 32 bit transfer.

The EISA bus, however, is still not sufficiently fast for computeroperations requiring large amounts of digital data to be quicklytransferred such as, for example, during hard disk access,communications, and video display. The transfer rate of the data overeither the ISA or EISA buses is a limiting factor in the operation ofthe computer system. As an example, the speed at which a video displaymay be updated is determined by the transfer rate of the video data.Therefore, when a high resolution color display utilizing many colorsneeds to be updated, the amount of video data required takes anunacceptably long time to transfer over the ISA or EISA buses.

To alleviate this data transfer bottleneck, computer systemmanufacturers began utilizing a special data, address and control bussystem that is closely coupled to the central processing unit (CPU) andrandom access memory (RAM). This bus operates at the same speed as theCPU, for example, 25-40 MHz. This high speed bus system is sometimesreferred to as the "host local bus". By utilizing the host local bus,disk and high-speed video data transfers between memory or the CPU needno longer pass through either the ISA or EISA bus interfaces with theirlimited bandwidth. A standard for video controller interfaces utilizingthe computer system local bus is being proposed by the Video ElectronicStandards Association as a standard for advanced local bus videocontrollers (this standard referred to hereinafter as "VESA/VL").

Thus, a personal computer system may utilize either an ISA or EISA busstandard and a host local bus standard such as the VESA/VL bus standard.Utilizing a combination of these bus standards is desirable andappropriate for particular types of peripherals, so that each of thesebus standards has utility for a particular purpose.

A personal computer system, in one conventional construction, isillustrated in FIG. 1. A computer housing 100 contains a power supply102, floppy disk drive 104, hard disk drive 106, and motherboard 108.Referring to FIG. 2, the motherboard 108 has input-output connectors 202adapted to receive either ISA or EISA peripheral device cards. Commonlyowned U.S. Pat. No. 5,036,481, issued Jul. 30, 1991 and incorporated byreference herein, more fully illustrates the construction of aconventional personal computer system.

The computer motherboard 108 or system planar mounts horizontally in thesystem 100 housing. The motherboard 108 contains the CPU and supportcircuits thereto and provisions for connection of random access memory(RAM). More recent motherboards may incorporate provisions for a VESA/VLbus interface device such as interface logic circuits and VESA/VLconnectors.

The motherboard 108 has a plurality of connectors 202 thereon for eitherISA or EISA bus devices, and may be adapted to interface with a VESA/VLdevice (not illustrated). Support circuits are also needed toaccommodate the various bus standards, and serial and parallel ports forthe particular computer system. These support circuits are frequentlyreferred to as "glue logic" and typically are located on the motherboard108. Making provisions for future additions and upgrades in the computersystem raises the complexity and cost of the computer system motherboard108 and may doom the motherboard to early obsolescence if newerinterface standards become popular. It is, therefore, an object of thepresent invention to provide an improved system and apparatus thatallows easy upgradability without burdening the cost of a base computersystem.

SUMMARY OF THE INVENTION

From a broad perspective, the present invention provides for operativelyand removably coupling a plurality of I/O expansion cards, host localbus interfaces and future system upgrades in a computer system withoutburdening the base cost thereof. The invention consists of a set ofconnectors on the computer system motherboard that are electricallyconnected to all data, address, control, power and ground signalsnecessary for expansion and upgrade of the computer system and a risercard or cards having the desired interface connectors and logic circuitsthereon.

The present invention allows the computer system to be expanded andupgraded at any time during manufacture or in the field. A simple andlow cost motherboard may be utilized in the manufacture of computersystems that can be sold at lower cost to a consumer because themotherboard is now common to all of the computer systems manufactured.The consumer need purchase only the minimum computer system needed and,when ready for more features, a riser card adapted for the desiredfeature upgrade may be plugged into the motherboard connectors.

In a preferred embodiment of the present invention, a host local busexpansion riser card may be inserted into the motherboard connectors.The riser card includes the necessary glue logic for properlyinterfacing to peripheral interface cards such as, for example, aVESA/VL video interface. The peripheral interface cards plug into theriser card. The VESA/VL card requires signals to and from the ISA I/Oand host local buses. This is easily accomplished by the presentinvention by having all necessary computer system signals available atconnectors placed in-line with the standard ISA or EISA connector slots.

In one aspect of the present invention, the I/O and host local busconnectors are in-line on the computer system motherboard allowing asubstantially unlimited number of options to be added now and in thefuture to a low cost base computer system. Features such as secondarycache cards, upgraded processors, or other host interface adapters forhigher modularity feature upgrades are possible. By appropriate designof the riser board, any number or combination of different interfacedevices may co-exist within the computer system. Features unheard ofwhen the computer system was purchased may be easily implemented at alater date without obsoleting the majority of the components of thecomputer.

In another aspect of the invention, a riser card has applicationspecific integrated circuit (ASIC) glue logic that creates the controlsignals required by a VESA/VL interface card. This riser card hasprovisions for and is adapted to connect to a plurality of either ISA orEISA interface cards along with the VESA/VL interface card. The risercard may be configured with a card cage housing module that contains andholds all of the interface cards so that this expansion card/riser cardmodule may be easily removed from the system motherboard.

In yet another aspect of the invention, a secondary cache memory andcontroller may be part of the riser expansion card. Placing applicationspecific circuitry in the riser card minimizes the amount of spacerequired on the motherboard, but allows functional support as needed.The motherboard need not be manufactured with extra support logic foranticipated future additions, so long as the motherboard makesavailable, by means of appropriately placed connectors thereon, acomplete set of data, address and control signals of the CPU and RAM. Inaddition, the motherboard connectors may be placed wherein theconnectors are close coupled to the CPU for efficient and reliabletransfer of high speed signals therebetween.

A feature of the present invention is having the motherboard connectorsin-line and spaced so that any combination of ISA or EISA bus, hostlocal bus or future bus expansions may be selectively accomplished byinserting an appropriate riser card or cards therein. By partitioningthe active logic on the riser card specific to the expansion interfacerequirements, the computer system manufacturer need not produce computersystem motherboards that anticipate future user requirements, standardsor technologies. The riser card is relatively trivial in cost comparedto the overall cost of the computer system. Thus, as new standardsemerge or technologies improve, a new riser card can embrace these newtechnologies or changing user requirements.

In another aspect of the invention, the motherboard in-line connectorsmay be utilized for connection of a riser or daughterboard having anewer processor or multiple coprocessors to further enhance or updatethe computer system. This allows the computer manufacturer to inventorystandard motherboards that may be configured later during final assemblyfor the latest processor technology. Thus, manufacturing of asubstantial part of the computer system need not be delayed while newproducts are developed.

Other and further objects, features and advantages will be apparent fromthe following description of the preferred embodiment of the invention,given for the purpose of disclosure and taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric partial view of a prior art computer system;

FIG. 2 is an isometric view of a prior art motherboard of FIG. 1;

FIG. 3 is a top plan view of a motherboard in accordance with apreferred embodiment of the present invention;

FIG. 4 is an elevational view of riser cards in accordance with apreferred embodiment of the present invention;

FIG. 5 is an elevational view of an enhancement card in accordance witha preferred embodiment of the present invention;

FIG. 6 is an exploded isometric view of a riser card and peripheral cardcage in accordance with a preferred embodiment of the present invention;

FIG. 7 is the apparatus of FIG. 6 illustrating peripheral card beinginserted therein;

FIG. 8 is the apparatus of FIGS. 8 and 9 illustrated in explodedisometric view in relation to a motherboard and computer housing inaccordance with the present invention;

FIG. 9 is a partial isometric view of a computer system in accordancewith the present invention; and

FIG. 10 is a schematic block diagram of a preferred embodiment of ariser card in accordance with the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings, the details of preferred embodiments ofthe present invention are illustrated. Like elements have the samenumber. In the drawings, the number 1100 (FIG. 9) designates generally acomputer system utilizing the present invention.

Referring now to FIG. 3, a motherboard is illustrated in top plan viewas utilized in the computer system 1100 (FIG. 9). The motherboard 300consists of a planar printed wiring board 302, input-output connectors304, and host local bus connectors 306. The motherboard 300 alsocontains logic circuits 310, random access memory 312 and microprocessor314. The connectors 304 and 306 are aligned such that a portion of ariser card or cards may be removably insertable therein.

Referring now to FIG. 4, an elevational view of a riser card of apreferred embodiment of the present invention is illustrated. Riser card402 has input-output connectors 404 attached thereto. The riser card 402has edge connections 406 that are removably insertable into themotherboard connector 304. There is a one-for-one signal connectioncorrespondence between the edge connections 406 and the connectors 404.The connectors 404 are adapted to receive input-output peripheralinterface cards such as, for example, ISA or EISA devices. The ISA orEISA interface cards are removably insertable into the connectors 404.

Riser card 410 may be utilized for connection of peripheral interfacedevices such as a VESA/VL interface to a host local bus closely coupledto the computer system central processing unit (CPU) or microprocessor.The card 410 has logic circuits thereon that are utilized for signaltranslation and control between the computer system local bus and aVESA/VL standard peripheral interface. The logic circuits generally arereferenced by the number 412 and may be, for example, logic circuits foran arbitration state machine (FIG. 10) and a slave master ready decode(FIG. 10).

The riser card 410 has connections 414 that are removably insertableinto the motherboard connector 306. Data, address and control signals ofthe host local bus are directly connected to the connector 306 and thedata, address, and some of the control signals are directly connected toVESA/VL connectors 416. The other control signals are processed in thelogic circuits 412. A VESA/VL interface card may be removably insertedinto connectors 416 and 404 which are in alignment. In addition, itshould be understood that the connector 306, and the connectors 416 maybe supersets of the VESA/VL interface.

Referring now to FIG. 5, logic cards consisting of circuit logic, memoryand a microprocessor are illustrated in plan view. The card 502 may be aVESA/VL interface card having connections 506 and 514 that are removablyinsertable into the connectors 304 and 306, respectively. The card 502is directly insertable into the motherboard connectors without anintermediate riser connector card therebetween. The signal card 502 maybe inserted into the connectors 304 and 306 which are aligned in a rowon the motherboard.

A logic card 504 having connections 514 is removably insertable into theconnector 306. The logic card 504 may consist of a cache memory andcontroller or a newer technology microprocessor that can replace theexisting microprocessor in the computer system or co-process therewith.The logic cards 502 and 504 allow for easy implementation of additionalfeatures or upgradability to the computer system.

The motherboard 302 need not contain extra logic circuitry for supportof desired peripheral expansion or addition of useful features to thecomputer system. This makes the initial manufacturing costs of thecomputer system less because the motherboard thereof is smaller, hasless circuitry and does not become obsolete as quickly as one havingpossible anticipated features that are never used or change with newertechnological implementations.

Referring to FIG. 6, an exploded isometric view of the riser cards 402and 410, and a card cage 602 is illustrated. The card cage 602 attachesto the riser cards 402 and 410 and is adapted to hold peripheralinterface cards, VESA/VL cards and other additions or enhancements tothe computer system. Commonly owned co-pending U.S. patent applicationSer. No. 07/967,903, entitled "Expansion Card/Riser Card Module forDesktop Computers", filed Oct. 27, 1992, more fully illustrates apreferred embodiment and application of this card cage apparatus, and isincorporated herein by reference for all purposes.

Referring now to FIG. 7, an exploded isometric view of a peripheralinterface card and the card cage 602 is illustrated. The card cage 602is adapted to hold interface cards 702 such as, for example, ISA or EISAcards, VESA/VL cards or other interface, expansion or upgrades asdesired. The cards 702 are slidably inserted into the cage 602 andconnect into the riser board connectors 404 and 416 (FIG. 6).

Referring now to FIG. 8, an exploded isometric view of a preferredembodiment of the present invention is illustrated. Once all of thecards 702 are inserted into the cage 602, the cage 602 containing thecards 702, may be attached to the computer system motherboard. The risercards 402 and 410 are substantially perpendicular to the plane of themotherboard 302 when inserted into the connectors 304 and 306. When thecage 602 is attached to the motherboard 302, all connections are made tothe desired peripheral cards 702 contained therein. FIG. 9 illustratesthe card cage 602 attached to and in place in the computer system 1100.

Referring now to FIG. 10, a schematic block diagram of a riser card inaccordance with a preferred embodiment of the present invention isillustrated. The riser card 410 consists of connectors 416, edgeconnections 414, and logic circuits 1002 and 1004. Signals consisting ofdata 1006, address 1008, and control 1010 are directly connected fromthe connections 414 to the connectors 416.

Some control signals 1212 and 1214 are first processed in the logiccircuits 1002 and 1004 before being connected to the connectors 416.Logic circuits 1002 and 1004 may be, for example, an arbitration statemachine and a slave-master ready decode, respectively. These activelogic circuits enable the computer system 1100 host local bus toproperly interface to an industry standard such as the VESA/VL standardwithout needing special interface or glue logic on the motherboard. Thisis a savings to the computer manufacturer which enables more efficientmanufacturing and cost competitive products. In addition, if aninterface standard is changed, then all that is required is thereplacement of the riser card 410 without obsoleting the more expensivemotherboard.

The present invention allows access to all data, address and controlbuses of the computer system. Any form of in-line connector schemes on asystem motherboard may be utilized. These connectors may supportperpendicular expansion riser cards, feature upgrade cards includingcache memory and newer processor complex or other host interace adaptersfor higher modularity feature upgrades. The present invention is notlimited to the size or number of in-line connectors that compose anexpansion slot or riser interface.

The riser card has interface connectors that are adapted to removablyreceive peripheral interface cards that may be held in a card cageintegrally attached to the riser card. The entire riser card, card cageand interface cards may be handled as a subassembly for fast and easyconnection to the computer system motherboard.

In another aspect of the invention, no riser card is needed. All of theadditional circuitry for either an addition in features or a systemupgrade may reside on a card that may be removably connected to themotherboard interface connectors. One skilled in the art of digitallogic and computer system control circuits could readily designappropriate control logic for various other aspects of the presentinvention using ASIC or other digital logic devices well known in theart.

The system and method of the present invention, therefore, is welladapted to carry out the objects and attain the ends and advantagesmentioned, as well as others inherent therein. While a presentlypreferred embodiment of the invention has been given for purposes ofdisclosure, numerous changes in the details of construction,interconnection and arrangement of parts will readily suggest themselvesto those skilled in the art, and which are encompassed within the spiritof the invention and the scope of the appended claims.

What is claimed is:
 1. An apparatus, in a computer system, for expandingthe functionality of the computer system, comprising:a plurality ofmotherboard connectors on a computer system motherboard, said pluralityof motherboard connectors connected to address, data, control, power andground buses of the motherboard; a riser card having a side edge portionremovably insertable into said motherboard connectors so as to connectto the address, data, control, power and ground buses of themotherboard; and said riser card having a plurality of riser cardconnectors adapted for connection to a plurality of peripheral deviceinterface cards and having application specific integrated circuits fortranslation of bus signals between the motherboard and interface cards.